Ice resurfacing machine

ABSTRACT

A self-propelled vehicle adapted to move over the surface of an ice rink and remove a layer of ice and subsequently spread a film of water over the shaved ice surface. The vehicle includes an ice-removing unit located at the rear of the vehicle and mounted such that the unit is pushed, rather than pulled, over the ice surface. The ice-removing unit comprises a cutting blade to shave the ice, and a rotating brush sweeps the ice and conveys the shavings forwardly to a transverse auger conveyor which delivers the shavings to an elevator that functions to convey the shavings to a tank on the vehicle. A hydraulic drive system is employed which enables an infinitely gradual application of torque to be applied to retain frictional engagement between the wheels and the ice.

United States Patent lnventor Kenneth R. Jones Mequon, Wis.

Appl. No. 869,247

Filed Oct. 24, 1969 Patented July 6, I971 Assignee Tennant Company Minneapolis, Minn.

Continuation-impart of application Ser. No. 624,080, Mar. 17, 1967, now mm No. 3,475,056.

ICE RESURFACING MACHINE 17 Claims, 7 Drawing Figs.

[1.8. Ci 299/24, 37/12, 180/648 Int. Cl ..E0lc 23/12, EOlh 5/ l2 Field of Search 299/24, 36-

37/12; ISO/6.48

[56] References Cited UNITED STATES PATENTS 3,044,193 7/ l 962 Zamboni 299/24 X 3,302,975 2/1967 Vandenberg 299/24 3,304,632 2/1967 Kotlur et al. 37/ l 2 Primary ExaminerErnest R. Purser Attorney-Andrus, Sceales, Starke & Sawall ABSTRACT: A self-propelled vehicle adapted to move over the surface of an ice rink and remove a layer of ice and subsequently spread a film of water over the shaved ice surface. The vehicle includes an ice-removing unit located at the rear of the vehicle and mounted such that the unit is pushed, rather than pulled, over the ice surface. The ice-removing unit comprises a cutting blade to shave the ice, and a rotating brush sweeps the ice and conveys the shavings forwardly to a transverse auger conveyor which delivers the shavings to an elevator that functions to convey the shavings to a tank on the vehicle. A hydraulic drive system is employed which enables an infinitely gradual application of torque to be applied to retain frictional engagement between the wheels and the ice.

ICE RESURFACING MACHINE This application is a continuation-in-part of application Ser. No. 624,080, filed Mar. 17, 1967 and entitled Ice Resurfacing Machine and now US. Pat. No. 3,475,056.

To provide a smooth, uniform surface for an ice rink, a thin layer of water is periodically applied to the surface of the ice and the water is frozen either by ambient temperatures or, in the case of an artificial rink, by a coolant which flows within coils embedded in the rink. The layer of ice acts as an insulating material, and as the ice builds up on an artificial rink the power requirements for cooling and freezing the water are correspondingly increased. Thus, from an economical standpoint it is necessary to remove a thin layer of the ice from the rink before applying a fresh film of water so that the layer of ice remains generally uniform in thickness throughout the season and the cooling requirements will be constant.

Moreover, the removal of a thin layer of ice results in a more uniform and smooth ice surface, for by shaving the ice, gouges or imperfections in the ice surface are eliminated or reduced in depth and a thinner film of water can thereby be applied to the shaved ice surface to restore the desired smooth and uniform surface characteristics.

Ice-resurfacing machines, in general, are self-propelled vehicles adapted to move over the surface of an ice rink and take a thin shaving cut from the surface, remove the shavings and thereafter spread a thin film of water over the shaved surface. The resurfacing machine of the invention includes an ice-removing unit or sled located at the rear of the vehicle and the forward end of the sled is connected by a pair of pivotable arms to the vehicle frame. The pivotal connection of the arms to the sled is ahead of the pivotal connection of the arms to the frame so that the sled is pushed across the ice surface, rather than being pulled, as the vehicle moves.

A blade is mounted transversely of the sled and is adapted I to engage and take a shaving cut of the ice. The ice shavings are swept from the ice surface and conveyed by a rotating brush to a transverse conveyor mounted for rotation ahead of the brush. The transverse conveyor delivers the shavings to the bottom of a vertical elevator which lifts the shavings to a bin or tank mounted on the vehicle.

The unit of the invention is hydraulically driven with a separate hydraulic motor for each wheel. With this individual hydraulic drive, the vehicle is extremely maneuverable and can pivot or turn about the geometrical center of the four wheels. Moreover, the use of individually driven wheels enables the power to be delivered to each wheel in a more precise or finite manner than can be achieved through use of the friction clutch of a conventional mechanical drive system. This enables the unit to be accelerated more gradually and prevents slipping or spinning of the wheels on the ice surface.

In the unit of the invention, the sled is both raised and lowered by a hydraulic cylinder unit. Thus, the sled is forced downwardly against the ice by hydraulic pressure so that the pressure being applied to the blade is not merely dependent on the weight of the sled. As the sled is pushed across the ice rather than being pulled or drawn, the pushing force tends to pivot the sled in one direction, while the hydraulic cylinder unit acting on the rear of the sled tends to pivot the sled in the opposite direction with the result that the forces acting on the blade are balanced. The balanced, downward acting forces on the blade enable the blade to take substantially heavier cuts than the conventional ice-resurfacing machine.

Moreover, the individual drive for the wheels and conveying equipment also aids in enabling the unit to take heavier cuts. With the use of a single engine acting through a standard gear transmission, as in the conventional machine, a heavy cut cannot usually be taken when the vehicle is moving slowly. At slow speeds, the engine is required to run at slow speed and the conveying equipment is also operating at slow speed, too slow to adequately remove the ice shavings generated by the heavy cut. With the unit of the invention, the conveying equipment is operated independently of the wheels so the unit can take heavy cuts at slow speeds and the conveying equipment can be operated at a speed sufficient to convey the ice shavings generated by the heavy cut.

The ice-resurfacing machine of the invention also provides a convenient adjustment for the blade height, as well as the angle of attack of the blade with respect to the ice. Thus, the operator can readily change the blade height to vary the depth of cut, as well as changing the angle of the attack of the blade on the ice.

The resurfacing machine of the invention utilizes a hydraulic drive to operate the brush and conveyors, as well as to propel the vehicle across the surface of the ice. In the preferred form of the invention a separate hydraulic motor is used for each of the wheels of the vehicle, and the use of separate hydraulic motors provides an extremely maneuverable vehicle which is capable of turning about the geometrical center of the four wheels. This enables the machine to move into small-radius comers and to readily maneuver around any obstructions on the rink.

Other objects and advantages'will appear in the course of the following description.

The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a plan view of the ice resurfacing machine of the invention;

FIG. 2 is a side elevation of the machine;

FIG. 3 is an enlarged vertical section of the rear portion of the machine and the sled;

FIG. 4 is a rear elevation of the machine with parts broken away in section;

FIG. 5 is a horizontal section taken along line 5-5 FIG. 3;

FIG. 6 is a schematic view of the hydraulic system for operation of the vehicle; and I FIG. 7 is a fragmentary, vertical cross section of the auger conveyor utilizing a modified form of resilient means to prevent accumulation of ice in the auger trough.

The drawings illustrate a self-propelled ice-resurfacing machine which includes a frame 1 and a body 2 is mounted on the frame. A series of wheels 3 are journaled on the frame 1. Extending rearwardly from the frame 1 is a platform 4 and an operators seat 5 is mounted on the platform.

The body is divided into a series of compartments and the forward compartment 6 contains an engine unit generally indicated by 7. The central portion of the: body defines a water tank or compartment 8 which contains water to be applied to the surface of the ice after the ice is shaved, while the rear portion of the body defines an ice tank 9 into which the shaved ice is delivered.

Mounted beneath the platform 3 is a sled 10 which includes a pair of sidewalls 11, a top wall 12, a rear wall 13 and a front wall 14. The walls 11, 12, 13 and 14 provide a generally rectangular, open-bottom shape for the sled 10.

The sled 10 is connected to the platform 3 by a pair of arms I5 having their upper ends pivotally connected by pins 16 to the platform 4, while the lower ends of the arms 15 are pivotally connected to brackets 17 which extend upwardly and forwardly from the front wall 14 of sled 10.

The sled 10 is adapted to be raised and lowered between a transporting position, in which the sled is positioned above the ice, to an operating position in which the sled rides on the surface of the ice. The sled is raised and lowered by a hydraulic cylinder 18 which is pivotally connected to angle brackets 19 secured to the rear surface of the platform 4. Piston rod 20 is slidable within the cylinder 18 and the lower end of rod 20 is pivotally connected to a pair of lugs 21 which extend upwardly from a crossbar 22 disposed above the top surface 12 of sled 10. As best shown in FIG. 4, the ends of crossbar 22 are pivotally connected to arms 23 and the forward ends of the arms 23 are pivotally connected to brackets 24 which are secured to the body 2. As the piston rod 20 is retracted within the cylinder 18, the crossbar 22 is moved upwardly to thereby pivot the arms 23 about the pivotal connection with brackets 24.

The sled is adapted to be raised in accordance with upward movement of the crossbar 22 and arms 23 and this is accomplished by angle brackets 25 which are secured to the arms 23. Studs 26 are secured within the lower flange of each angle bracket and extend through the upper surface 12 of sled 10. The lower ends of studs 26 are provided with enlarged heads 27, and as the arms 23 pivot upwardly the enlarged heads 27 engage the top wall 12 to thereby lift the sled 10. The studs 26 are positioned, in a fore-and-aft direction, slightly to the rear of the center of gravity of the sled 10 so that as the arms 23 pivot upwardly, the sled will be moved vertically and the forward end of the sled will tilt downwardly. This tilted position, in which the front end of the sled is down and the rear end is up, is an advantage when transporting, for the upwardly tilted rear end of the sled provides additional ground clearance when the vehicle is driven up or down a ramp or other incline.

The ice is shaved by a blade 28 which extends transversely of the sled 10 and is mounted on the lower flange of an angle support 29. The forward portion of the lower flange of angle support 29 is pivotally connected to the central portion of arms'30, while the forward ends of the arms 30 are pivotally connected to the sidewalls 11 of the sled. Pivotally connected to the rear ends of arms 30 are vertical supports 31 which extend upwardly adjacent the rear wall 13. The upper end of each vertical support 31 carries a nut 32 and an adjusting screw 33 is threaded within a boss in the top plate 12, as well as in the nut 32, so that threading of the screw 33 will tend to pivot the arms 30 to thereby raise and lower the blade 28. To guide the adjusting screws in movement, the lower end 34 of each screw has a reduced diameter and is slidably received within a guide ring 35 mounted on the central portion of each vertical support 31.

In addition to the adjustment for blade height which determines the depth of cut, a second adjustment is provided to vary the angularity of the blade with respect to the ice. In this regard an adjusting screw 36, as shown in FIG. 4, is located centrally of the width of the sled 10 and is threaded within a boss formed on the top wall 12 of sled 10 and within a nut 37 which is pivotally connected to angle brackets 38 mounted on the vertical flange of the blade support 29. By threading the adjusting screw 36 into the nut 37, the angularity of the blade 28 can be varied as desired.

The machine of the invention has the ability to take a heavy cut due to the manner in which the sled is connected to the propelling vehicle. The pushing force exerted by the vehicle on the sled and the resisting force of the cutting blade act on the connecting linkage between the sled and the vehicle to create a downward force. This force is counterbalanced by the force of the hydraulic cylinder 18, with the blade as the fulcrum. Thus the greater the resistance caused by the depth of cut, the greater the downward force tending to penetrate the blade into the ice.

As previously mentioned, the forward edge of the blade is adapted to engage the surface of the ice and take a shaving cut. The ice shavings are then swept from the ice surface and conveyed forwardly by a brush 39 mounted on a shaft 40 which is journaled within the sidewalls 11 of sled 10. The brush is located within a generally curved housing 41, and as the brush rotates, the bristles engage the surface of the ice and convey the shavings upwardly in the direction of the arrow in FIG. 3 against the housing 41. The upper end of housing 41 serves to direct the shavings forwardly toward a pair of transverse augers 42 which are mounted on shaft 43. The auger shaft 43 is journaled within the sidewalls 11 of the sled l0 and the pitch of one of the augers 42 is opposite to the pitch of the other auger so that each auger will serve to convey the ice shavings toward the center of the width of the sled 10. Attached between the ends of the flighting of the augers 42, at the midportion of the shaft 43, is a paddle 44 which extends axially of the shaft 43. The shavings being conveyed toward the center portion of the shaft 43 by augers 42 will be engaged by the paddle 44 and thrown forwardly toward a vertical conveyor or elevator, as will hereinafter be described.

The augers 42 are supported within a transverse trough 45, and, as best shown in FIGS. 3 and 5, covers 46 are hinged to the forward edge of trough 45 and extend upwardly over the auger sections 42. The rear ends of covers 46 are supported from the top wall 12 of sled 10 by a series of springs 47 or other resilient members. The connection of the covers 46 to the sled wall 12 by the resilient springs 47 permits the covers 46 to jiggle or vibrate as the vehicle is moved over the ice surface and thereby prevents arching or other accumulation of ice shavings within the forward end of the sled 10.

Located between the hinged covers 46 is a fixed cover member 48 which is also connected to the forward edge of trough 45 and extends rearwardly over the area of the transverse conveyor containing the paddle 44. As best shown in FIG. 5, the cover 48 extends rearwardly beyond the rear ends of the hinged covers 46 and serves to direct the ice shavings being thrown forwardly by paddle 44 toward the vertical conveyor or elevator.

The brush 39 and the auger sections 42 are driven by a hydraulic motor 50 which is mounted on the top wall 12 of sled 10. As best shown in FIGS. 1 and 4, the drive shaft 51 of motor 50 is journaled within a pair of bearing brackets 52 and the shaft 51 carries a pair of sprockets 53 and 54. Sprocket 53 is connected by chain 55 to a sprocket 56 on the brush shaft 40, while the sprocket 54 is connected by chain 57 to a sprocket 58 on auger shaft 43. Thus, rotation of the motor drive shaft 51 serves to rotate both the brush and the auger in the directions indicated by the arrows in FIG. 3.

As previously mentioned, the ice shavings are conveyed forwardly by auger sections 42 and paddle 44 through an opening 49 in trough 45, and are moved upwardly to the tank 9 by an elevator or a vertical auger 59 mounted within a housing 60. The lower end of the auger shaft 61 is journaled within the bottom wall 62 of housing 60, while the upper end of auger shaft 61 extends through the top wall 63 of housing 60 and is operably connected to the drive shaft of a hydraulic motor 64. The lower end of housing 60 is provided with an inlet opening 65 located in alignment with opening 49 in conveyor trough 45.

The upper end of the housing 60 is provided with an opening disposed in alignment with an opening in the body 2 so that the shavings being conveyed upwardly within the housing will be discharged by the auger 59 into the ice tank 9.

The housing 60 is pivotally connected to the body 2 through a pair of angle brackets 66 which are welded to the housing 60 and connected by bolts to body 2. The brackets 66 provide the sole connection of the housing 60 to the vehicle body so that the lower end of the housing can move, vibrate or jiggle, during operation of the machine and thereby prevent the buildup or accumulation of ice at the inlet to the housing 60.

The blade 28 takes a cut of ice from the surface of the rink and the shavings are conveyed forwardly by the brush 28 and deflected by the housing 41 to the auger sections 42. The auger sections serve to convey the shavings toward the center of the sled where it is propelled by the paddle 44 through the opening 49 in trough 45 and into the opening 65 in the lower end of vertical conveyor housing 60. The auger 59 then conveys the shavings upwardly within the housing, discharging the shavings into the tank 9.

The housing 60 is pivotally connected to the body 2 through a pair of angle brackets 66 which are welded to the housing 60 and connected by bolts to body 2. The brackets 66 provide the sole connection of the housing 60 to the vehicle body so that the lower end of the housing can move, vibrate or jiggle, during operation of the machine and thereby prevent the buildup or accumulation of ice at the inlet to the housing 60.

The blade 28 takes a cut of ice from the surface of the rink and the shavings are conveyed forwardly by the brush 28 and deflected by the housing 41 to the auger sections 42. The auger sections serve to convey the shavings toward the center of the sled where it is propelled by the paddle 44 through the opening 49 in trough 45 and into the opening 65 in the lower end of vertical conveyor housing 60. The auger 59 then conveys the shavings upwardly within the housing, discharging the shavings into the tank 9.

The unit of the invention also applies a thin coating of water to the shaved ice. As shown in FIG. 3, a manifold 67 is mounted on the rear wall 13 of sled l0 and extends substantially the length of the sled. Water is supplied to the manifold 67 through a hose 68 which is connected to the lower end of the water tank 9. Spaced along the manifold 67 are a series of nozzles 69, and water is discharged through the nozzles into the open, upper end of a bag 70 which rides on the surface of the ice. The upper end of the bag 70 is supported by a generally rectangular frame 7 I mounted on the rear wall 13 of sled 10. The bag 70 is formed of a flexible, water porous material such as canvas or the like and the water is discharged evenly from the bag onto the scraped surface of the ice in the form of a thin uniform film.

Located ahead of the bag 70 is a resilient scraper 72 which is mounted through a bar 73 to the lower end of wall 13. The scraper 72, made of rubber or other resilient material, is adapted to scrape along the surface of the ice and prevent shavings from being coated with the layer of water. This insures that the water will not be applied over ice shavings or other particles which may tend to provide a rough surface.

Attached to the sidewalls 11 of the sled are guide bars 74 which extend forwardly from the sled. Bars 74 are provided with bent forward ends that extend inwardly at an angle toward the fore-and-aft centerline of the vehicle. The kick boards located along the edge of the rink are often irregular, and the diagonal forward end of the guide bar 74 rides against the kick boards and prevents the sled from catching on any protruding board or edge. Normally, there will be an accumulation of ice shavings along the kick boards due to the skating activity on the rink, and the guide bars 74 are formed with a minimum height, or depth, so that the accumulation of ice shavings along the kick boards will ride over the guide bar and into the sled, rather than being plowed along the kick board as would occur if a deep or high guide bar was utilized.

As previously mentioned, the vehicle itself, as well as the brush 39 and augers 42 and 59, are driven hydraulically. The engine 7, which is located in forward compartment 6, has a pair of drive shafts 75 which extend from opposite ends of the engine, as shown in FIG. 1. One of the shafts 75 is connected to a constant volume pump 76, while the other shaft serves to drive a variable volume pump 77.

Each of the wheels 3 is driven by an individual hydraulic motor and, as best shown in FIG. I, each wheel is mounted on an axle 78 which is joumaled within the frame 1 of the vehicle. Each axle 78 carries a sprocket 79 which is connected by a chain 80 to a sprocket 81 on the drive shaft 82 of a hydraulic motor 83. The hydraulic motors, as shown in FIG. 1, are indicated by 83a, 83b, 83c and 83d, for the four individual wheels.

FIG. 6 illustrates the hydraulic system for the ice resurfacing machine. As shown in this drawing, hydraulic fluid is supplied through line 84 from a reservoir 85 to the variable volume pump 77, and the discharge line 86 of pump 77 is con nected to a flow diverter 87 which divides the flow. One of the outlet lines 88 from flow divider 87 is connected to a threeway valve unit, indicated generally by 89. Valve 89 is manually operated and serves to either operate the motors 83a and 83b in a forward or reverse direction. Lines 90 and 91 connect valve 89 with the motors 83a and 83b, respectively. The outlet from motor 830 is connected to line 93, while the outlet from motor 83b is connected to line 92. In addition, a bypass line 94 connects the lines 92 and 93. Line 92 and 93 are connected through valve 89 to the discharge line 95 which is connected to the reservoir 85.

Valves 96, 97 and 98 are located in lines 93, 90 and 94, respectively, and by selective opening and closing of these valves, the flow of hydraulic fluid can be directed to either or both of the motors 83a or 83b. Valves 96, 97 and 98 are shown as separate valves, but in practice, it is contemplated that these valves would all be located in a common valve block.

Line 99, which is connected to flow diverter 87, is also connected to a valve 100, similar to valve 89, and the discharge lines 101 and 102 from valve are connected to motors 83c and 83d in a manner similar to that described with respect to motors 83a and 83b. Fluid is discharged from the motors 83c and 83d through lines 103 and 104, respectively, and a bypass line 105 connects lines 103 and 104. Lines 103 and 104 are connected through valve 100 to discharge line 106 which leads to the reservoir 85.

Valves 107, 108 and 109, which are similar to valves 96, 97 and 98, are located in lines I03, I02 and 105, respectively, and by opening or closing these valves, the flow of fluid can be directed to either of the motors 830 or 83d, or both motors, as desired. Thus, by proper actuation of the valves, the hydraulic fluid can be selectively directed to any one of the four motors 83a-83d, or to any pair of motors and the flow of hydraulic fluid to the motors can be varied to provide the optimum speed-power relationship for transporting over the highway and for ice resurfacing. For example, a series arrangement of motors 83a and 83b can be provided by opening valve 98 and closing valves 96 and 97 to thereby obtain high speed-low torque conditions which is adaptable for use on surfaces with limited traction, such as ice. A parallel arrangement of motors 83a and 83b is obtained by closing valve 98 and opening valves 96 and 97. This provides low-speed high-torque conditions to be used when the machine is heavily loaded with ice shavings or on high-traction surfaces. Similar series and parallel arrangements of motors 83c and 83d can be obtained by manipulation of valves 105, 107 and 108.

The hydraulic drive system of the invention provides increased maneuverability for the vehicle. In the conventional four-wheel drive ice-resurfacing machine, in which all four wheels are driven by a single engine or power source, the wheels all operate at the same speed and in the same direction so that steering is accomplished by turning the front wheels. During the turn, one pair of wheels will be moving along a larger radius of curvature than the other pair of wheels, and as the wheels are all operating at the same speed slippage must necessarily occur which results in a loss of traction. However, with the hydraulic system of the invention, steering is accomplished by increasing or decreasing the speed of the pair of wheels on either the right or left side of the machine, and during a turn, the pair of wheels moving along the larger radius of curvature will be operating at a higher speed than the other pair of wheels moving along a smaller radius, with the result that there will be no loss of traction during turning. This feature is of particular importance when dealing with a low-traction surface, such as ice.

As an added advantage, the hydraulic system of the invention provides extreme maneuverability for the machine. It is possible, if desired, for the machine to spin about its geometrical center by operating the wheels on one side in the reverse direction to the direction of rotation of the wheels on the opposite side. Thus, by changing the speed or direction of rotation of the motors 83a and 83b on one side of the machine with respect to the motors 83c and 83d on the opposite side of the machine it is possible to provide an almost infinite degree of maneuverability.

As shown in FIG. 6, hydraulic fluid is introduced through line 110 to pump 76 and is discharged through line 111 to a valve unit 112. When the valve unit 1112 is in one operating position, line 111 will be in communication with line 113 of the hydraulic cylinder 18 which serves to raise the sled l0 and fluid is withdrawn from the opposite end of the cylinder through line 114. Line 114 is connected through valve 112 to line 115 which is connected to a second valve unit 116. When the manual valve unit I16 is in one operating position, line 115 will be in communication with line 117. A flow divider 118 is located in line 117 and divides the flow into lines'll9 and 120 which are connected to hydraulic motors 50 and 63, respectively. The motor 50 serves to drive the horizontal augers and the brush, while the motor 63 functions to drive the vertical conveyor 59. Fluid discharged from the motors 50 and 63 is conducted through line 121 to valve 116 and then through line 122 to reservoir 85.

By reversing the position of valve unit 112, fluid in line 111 will be directed through line 114 to the upper end of cylinder 18 which results in the sled being lowered. Similarly, by reversing the position of valve unit 116, fluid from line 115 will flow through line 121 to operate the motors 50 and 63 in the reverse direction.

As best illustrated in FIG. 1, the shaft 75 extends transversely of the vehicle with the pump 76 and 77 being located on opposite sides of the engine 7. This arrangement facilitates maintenance for the engine and pumps can be serviced by merely removing the front shroud of the vehicle body.

A provision is made to incorporate shock-absorbing action for the fluid in the return lines 92 and 104. A shock absorber 123 is connected by line 124 to return line 92, and similarly a shock absorber 125 is connected by line 126 to the return line 104. The shock absorbers can be conventional types commonly used in hydraulic systems and as illustrated, each shock absorber includes a flexible diaphragm 127 and, the lower portion of each shock absorber beneath the diaphragm is filled with fluid from the hydraulic system. A spring 128, or other resilient member, is interposed between the upper surface of the diaphragm and the end of the shock-absorbing cylinder. When lines 92 and 104 are closed by operation of valves 89 and 100 a high-pressure surge is developed at motors 83b and 83d and this high-pressure fluid surge is cushioned by the shock absorbers 124 and 125.

If the ice-resurfacing machine travels downhill, as for example, when moving down an inclined ramp, the motors 83 are driven by the wheels and act as hydraulic pumps. As valves 89 and 100 are closed when the machine is moving downhill, the pumping action of motors 83 tends to provide cavitation in lines 90 and 91, 101 and 102. If the hydraulic fluid was pumped completely from the lines 90, 91, 101 and 102 by the pumping action of motors 83, the ice-resurfacing machine would travel downhill with uncontrolled speed. To prevent this situation, an anticavitation feature is incorporated in the hydraulic system. As shown in FIG. 6 a bypass line 129 is connected between lines 106 and 92 and a check valve 130 is incorporated in the line 129. In addition, line 131 connects line 130 with the line 91 and a second check valve 132 is connected in line 133. The check valves 132 and '134 are set to open at a predetermined pressure to permit fluid to flow from line 106 to either line 91 or 92 and thereby bypass the valve 89.

If the ice-resurfacing machine is moving forwardly down an incline the motor 83a will operate as a pump to reduce the pressure in line 91. When the pressure in line 91 decreases to a value below the setting of check valve 132, the check valve will open to permit fluid to flow from line 106 to 91 to thereby bypass the valve 89 and prevent cavitation in line 91. Check valve 130 operates in a similar manner when the vehicle moves rearwardly down an inclined slope and will open to permit the flow of fluid from line 106 to line 92 when the pressure in line 92 drops below the preset level.

in addition, a similar anticavitation feature is utilized in connection with motors 83a and 83d. In this connection a line 133 is connected between line 106 and return line 104 and check valve 134 is connected in line 133. In addition, line 135 is connected between line 133 and line 101 and check valve 136 is located in line 135. The check valves 134 and 136 operate in a manner similar to that described with respect to check valves 130 and 132 to prevent cavitation in lines 101 and 104 when the ice-resurfacing machine moves down an incline.

To improve the efficiency of the hydraulic system, one or more of the return lines 84, 95, 110 and 122 can be run through the tank 9 in the vehicle which contains the ice shavings. This acts in a heat exchange capacity to transfer heat from the oil in lines 85, 95, 110 and 122 to the ice, thereby cooling the oil and melting the ice.

in order to provide a more gradual or softer stopping action for the machine, the discharge ports in valves 89 and 100 are arranged so that the return lines 92 and 104 are closed slightly after the inlet lines and 91 and 101 and 102, respectively, are closed. By delaying the closing of lines 92 and 104 a softer stop is provided which eliminates the jolt which might occur if all the lines were closed at the same instant.

The hydraulic system of the invention provides an infinitely gradual application of torque which retains the static frictional contact between the wheels and the ice surface. Under heavy load conditions, when the blade is taking a relatively thick shaving cut, it is difficult to maintain frictional contact between the wheels and the ice surface. However, by use of the hydraulic system of the invention an infinitely gradual application of torque can be achieved which will retain frictional engagement between the wheels and the ice surface. This is an important advantage over a conventional drive system incorporating a clutch, for with a clutch the application of torque is more abrupt and a low level of torque cannot normally be applied without slipping of the clutch.

FIG. 7 shows a modified form of the structure designed to prevent the accumulation or arching of ice shavings above the transverse auger. In this embodiment, an auger 137, corresponding to auger 42, is mounted for rotation in housing 138, similar in structure to auger housing 45. The forward portion of auger housing 138 is connected to the forward wall 139 of the sled, and an opening 140 is provided in housing 138 through which the ice shavings are conveyed to the elevator.

A flexible rubberlike sheet 141 is draped over the auger flighting with one edge of the sheet being connected to front wall 139 and the other edge being connected to the top wall 142 of the sled. The sheet extends the length of the auger 137 and during operation, the edge of the auger flighting rides against the sheet 141 and tends to continually flex or deform the sheet. This continuous flexing of the sheet prevents buildup of ice in the upper portion of the sled above the auger.

The ice-resurfacing machine of the invention is a selfpropelled unit which is capable of taking a relatively heavy shaving cut of ice from a rink, depositing the shavings in a tank on the vehicle and applying a thin layer of water to the resurfaced ice. The brush 39, which is located ahead of the blades, serves to sweep the shavings from the ice surface and convey the shavings to the horizontal auger sections 42 which in turn act to deliver the shavings to the vertical auger 59.

If a transverse auger, similar to auger 42, was mounted ahead of the blade and the brush 39 eliminated, it would be necessary for a relatively large quantity of shavings to be accumulated before the auger would act to convey the shavings to the elevator 59. However, with the use of the brush 39, the ice shavings are continually swept from the ice surface and delivered to the auger 42 and this eliminates any accumulation of shavings ahead of the blade and prevents arching of the ice shavings in the rear portion of the sled above the blade.

The resilient connection of the covers 46 to the sled, or the use of the flexible cover member 141, prevents the buildup of ice over the auger sections 42, and similarly the freely movable lower end of vertical housing 60 eliminates any possible accumulation of ice in the opening 65 of the housing.

The ice delivered to the tank 9 can be either melted or removed from the tank by conveying equipment. For example, a sprinkler head can be mounted in the wall bordering the tank 9 and by connecting the sprinkler head through a hose to a source of warm water after the resurfacing operation has been complete, water will be sprayed on the shavings to melt the same. Altemately, the side of the tank 9 can be provided with a hinged door, and the shavings can be discharged, either manually or by the use of power equipment, though the door to the exterior.

The sled 10 is raised and lowered through operation of the hydraulic cylinder 18. The sled can be readily raised to a position above the ice for transporting and when resurfacing, the pressure of the hydraulic fluid in cylinder 18 can be utilized to urge the sled downwardly against the ice and thereby provide a more uniform cutting action. As a further point of novelty, the sled, instead of being drawn or pulled across the ice, is

pushed by the vehicle. This pushing force tends to pivot the sled counterclockwise, as shown in FIG. 3, and this force is balanced by the downward force of the hydraulic cylinder on the rear end of the sled which acts to pivot the sled clockwise. Thus, a positive, yet balanced, downwardforce is applied to the blade during the resurfacing.

As eachof the wheels is driven by an individual hydraulic motor, and as hydraulic fluid can be individually supplied to each of the motors, the vehicle is extremely maneuverable enabling the vehicle to move into the corners of the rink and to maneuver around obstructions on the rink.

While the drawings illustrate an ice-resurfacing machine adapted for resurfacing larger sized rinks, it is contemplated that a similar, but smaller, electrically driven unit, incorporating electric motors in place of the hydraulic motors, can be used for smaller indoor rinks.

I claim:

1. In an ice-resurfacing machine, a self-propelled vehicle having a pair of wheels and having a tank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a'shaving cut thereof and conveying the ice shavings to said tankon the vehicle, a first hydraulic circuit, a first hydraulic motor operably connected to one of said wheels and connected in said hydraulic circuit, a second hydraulic motor operably connected to a second of said wheels and connected in said hydraulic circuit in parallel with said first motor, first valve means connected in said hydraulic circuit in series with said first motor, second valve means connected in said hydraulic circuit in series with said second motor, and third valve means connected in said hydraulic circuit and arranged in parallel with said first and second valve means so that opening of said third valve means will bypass said first and second valve means and operate said first and second motors.

2. The machine of claim 1, including a second hydraulic circuit including a reservoir for hydraulic fluid mounted on the vehicle, and three-way valve means interconnecting said first and second hydraulic circuits, said three-way valve means having a forward position whereby fluid will be supplied from said second hydraulic circuit in one direction through said first hydraulic circuit and having a reverse position whereby fluid will be supplied in the opposite direction through said first hydraulic circuit and having a closed position whereby fluid will not be supplied to said first hydraulic circuit.

3. The machine of claim-l, wherein said vehicle has a second pair of wheels, and said machine includes a third motor operably connected to a first of said second pair of wheels, a fourth motor connected to the second of said second pair of wheels, a second hydraulic circuit with said third and fourth motors being connected in parallel in said hydraulic circuit, fourth valve means connected in said second hydraulic circuit in series with said third motor, fifth valve means connected in said second hydraulic circuit in series with said fourth motor, and sixth valve means connected in said second hydraulic circuit in parallel with said fourth and fifth valve means and arranged so that opening of said sixth valve means will bypass said fourth and fifth valve means and supply hydraulic fluid to both said third and fourth motors.

4. The machine of claim 1, and including means for varying the flow of hydraulic fluid in said first hydraulic circuit to thereby vary the speed of said motors.

5. In an ice-resurfacing machine, a self-propelled vehicle having a series of wheels and having a tank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a shaving cut thereof and conveying the ice shavings to the tank on the vehicle, drive means operably connected to at least one of the wheels and including a hydraulic system, said hydraulic system comprising a hydraulic motor, a reservoir for hydraulic fluid and a conduit for. conducting fluid from the hydraulic motor to the reservoir, heat transfer means for passing the hydraulic fluid in said conto thereby cool the hydraulic fluid and melt the ice.,

6. The machine of claim 5, wherein said hydraulic system includes a series of hydraulic motors with each motor being operable connected to one of said wheels and a series of conduits connecting each hydraulic motor to the reservoir, said heat transfer means arranged topass the hydraulic fluid in each of said conduits in heat transfer relation with the ice shavings in the tank.

7. The machine of claim 5, wherein said conduit includes a portion disposed within said tank.

8. In an ice-resurfacing machine, aself-propelled vehicle having a series of wheels and having attank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a shaving cut thereof and conveying the ice shavings to the tank on the vehicle, a hydraulic system including a hydraulic motor operably con nected to at least one of said wheels, a reservoir for hydraulic fluid, first conduit means connecting the motor to the reservoir, second conduit means connecting the reservoir to the motor 'and pumping means for pumping fluid through said system, said hydraulic system also including first valve means in said first conduit means for opening and closing said first conduit means, and shock-absorbing means operably connected in said first conduit means and located between said first valve means and the motor for absorbing the shock in said first conduit means when said first valve means is abruptly closed.

9. The machine of claim 8, and including second valve means disposed in said second conduit means-for opening and closing said second conduit means, said first and second valve means being arranged so that they open and close in unison.

10. The machine of claim 8, and including means for reversing the flow of fluid through said first and second conduit means.

11. In an ice-resurfacing machine, a self-propelled vehicle having a series of wheels and having a tank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a shaving cut thereof and conveying the ice shavings to the tank on the vehicle, a hydraulic system including a hydraulic motor operably connected to at least one of said wheels, a reservoir for hydraulic fluid, first conduit means connecting the motor to the reservoir, second conduit meansconnectiing the reservoir to the motor and pumping means for pumping fluid through said system, said hydraulic system also including first valve means connected in said first conduit means for opening and closing said first conduit means, bypass conduit means connecting the portion of said first conduit means located between said first valve means and the motor with the reservoir, second valve means located in said bypass conduit means, and means responsive to a given decrease in fluid pressure in said portion of the first conduit means when said first valve means is closed due to forward travel of said machine down an incline for opening said second valve means and permitting flow of fluid to said portion of the first conduit means.

12. The machine of claim 11, wherein said second valve means is a check valve which is arranged to prevent flow of fluid from said portion of the first conduit means to said reservorr.

13. The machine of claim 11, and including third valve means connected in said second conduit means for opening and closing said second conduit means, said third valve means being arranged to open and close in unison with said first valve means located between said second valve means and the motor with the reservoir, fourth valve means located in said second bypass conduit means, and means responsive to a given decrease in fluid pressure in said portion of the second conduit means when said third valve means is closed due to reverse travel of said machine down an incline for opening said fourth valve means and permitting flow of fluid to said portion of the second conduit means.

15 In a machine adapted to perform a working operation and having a tank to receive material removed from the surface, means connected to the vehicle for engaging the surface and conveying the material from the surface to said tank on the vehicle, a first hydraulic circuit, a first hydraulic motor operably connected to one of said wheels and connected in said hydraulic circuit, a second hydraulic motor operably connected to a second of said wheels and connected in said hydraulic circuit in parallel with said first motor, first valve means connected in said hydraulic circuit in series with said first motor, second valve means connected in said hydraulic circuit in series with said second motor, and third valve means connected in said hydraulic circuit and arranged in parallel with said first and second valve means so that opening of said third valve means will bypass said first and second valve means and operate said first and second motors.

l6 The machine of claim 15, wherein said vehicle has a second pair of wheels, and said machine includes a third motor operably connected to a first of said second pair of wheels, a fourth motor connected to the second of said second pair of wheels, :2 second hydraulic circuit with said third and fourth motors being connected in parallel in said second hydraulic circuit, fourth valve means connected in said second hydraulic circuit in series with said third motor, fifth valve means connected in said second hydraulic circuit in series with said fourth motor, and sixth valve means connected in said second hydraulic circuit in parallel with said fourth and fifth valve means and arranged so that opening of said sixth valve means will bypass said fourth and fifth valve means and supply hydraulic fluid to both said third and fourth motors.

17. The machine of claim 15, wherein said first pair of wheels are located on one side of the vehicle and the second pair of wheels are located on the opposite side of the vehicle.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,591,236 Dated Patent No. July 6, 1971 Inventor(s) Kenneth R. Jones.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

F I I E Column 2, line 44, After "body" insert ---2-, Column 4,

Cancel lines 62 through 75, Column 5, Cancel lines 1 and 2, I Column 7, line 35, cancel "fluid" and substitute therefor ---liquid-- Signed and sealed this Ltth day of January 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK Acting Commissioner of Patents EDWARD MJLETCHER, JR. Attesting Officer FORM FO-IOSO (10-69) uscommoc 6O376-P59 U 5 GOVERNMENT PRINTlNG OFFICE I969 0368'33l 

1. In an ice-resurfacing machine, a self-propelled vehicle having a pair of wheels and having a tank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a shaving cut thereof and conveying the ice shavings to said tank on the vehicle, a first hydraulic circuit, a first hydraulic motor operably connected to one of said wheels and connected in said hydraulic circuit, a second hydraulic motor operably connected to a second of said wheels and connected in said hydraulic circuit in parallel with said first motor, first valve means connected in said hydraulic circuit in series with said first motor, second valve means connected in said hydraulic circuit in series with said second motor, and third valve means connected in said hydraulic circuit and arranged in parallel with said first and second valve means so that opening of said third valve means will bypass said first and second valve means and operate said first and second motors.
 2. The machine of claim 1, including a second hydraulic circuit including a reservoir for hydraulic fluid mounted on the vehicle, and three-way valve means interconnecting said first and second hydraulic circuits, said three-way valve means having a forward position whereby fluid will be supplied from said second hydraulic circuit in one direction through said first hydraulic circuit and having a reverse position whereby fluid will be supplied in the opposite direction through said first hydraulic circuit and having a closed position whereby fluid will not be supplied to said first hydraulic circuit.
 3. The machine of claim 1, wherein said vehicle has a second pair of wheels, and said machine includes a third motor operably connected to a first of said second pair of wheels, a fourth motor connected to the second of said second pair of wheels, a second hydraulic circuit with said third and fourth motors being connected in parallel in said hydraulic circuit, fourth valve means connected in said second hydraulic circuit in series with said third motor, fifth valve means connected in said second hydraulic circuit in series with said fourth motor, and sixth valve means connected in said second hydraulic circuit in parallel with said fourth and fifth valve means and arranged so that opening of said sixth valve means will bypass said fourth and fifth valve means and supply hydraulic fluid to both said third and fourth motors.
 4. The machine of claim 1, and including means for varying the flow of hydraulic fluid in said first hydraulic circuit to thereby vary the speed of said motors.
 5. In an ice-resurfacing machine, a self-propelled vehicle having a series of wheels and having a tank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a shaving cut thereof and conveying the ice shavings to the tank on the vehicle, drive means operably connected to at least one of the wheels and including a hydraulic system, said hydraulic system comprising a hydraulic motor, a reservoir for hydraulic fluid and a conduit for conducting fluid from the hydraulic motor to the reservoir, heat transfer means for passing the hydraulic fluid in said conduit in heat transfer relation with the ice shavings in said tank to thereby cool the hydraulic fluid and melt the ice.
 6. The machine of claim 5, wherein said hydraulic system inclUdes a series of hydraulic motors with each motor being operable connected to one of said wheels and a series of conduits connecting each hydraulic motor to the reservoir, said heat transfer means arranged to pass the hydraulic fluid in each of said conduits in heat transfer relation with the ice shavings in the tank.
 7. The machine of claim 5, wherein said conduit includes a portion disposed within said tank.
 8. In an ice-resurfacing machine, a self-propelled vehicle having a series of wheels and having a tank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a shaving cut thereof and conveying the ice shavings to the tank on the vehicle, a hydraulic system including a hydraulic motor operably connected to at least one of said wheels, a reservoir for hydraulic fluid, first conduit means connecting the motor to the reservoir, second conduit means connecting the reservoir to the motor and pumping means for pumping fluid through said system, said hydraulic system also including first valve means in said first conduit means for opening and closing said first conduit means, and shock-absorbing means operably connected in said first conduit means and located between said first valve means and the motor for absorbing the shock in said first conduit means when said first valve means is abruptly closed.
 9. The machine of claim 8, and including second valve means disposed in said second conduit means for opening and closing said second conduit means, said first and second valve means being arranged so that they open and close in unison.
 10. The machine of claim 8, and including means for reversing the flow of fluid through said first and second conduit means.
 11. In an ice-resurfacing machine, a self-propelled vehicle having a series of wheels and having a tank to receive ice shavings, ice-removing means connected to the vehicle for engaging the ice surface and taking a shaving cut thereof and conveying the ice shavings to the tank on the vehicle, a hydraulic system including a hydraulic motor operably connected to at least one of said wheels, a reservoir for hydraulic fluid, first conduit means connecting the motor to the reservoir, second conduit means connecting the reservoir to the motor and pumping means for pumping fluid through said system, said hydraulic system also including first valve means connected in said first conduit means for opening and closing said first conduit means, bypass conduit means connecting the portion of said first conduit means located between said first valve means and the motor with the reservoir, second valve means located in said bypass conduit means, and means responsive to a given decrease in fluid pressure in said portion of the first conduit means when said first valve means is closed due to forward travel of said machine down an incline for opening said second valve means and permitting flow of fluid to said portion of the first conduit means.
 12. The machine of claim 11, wherein said second valve means is a check valve which is arranged to prevent flow of fluid from said portion of the first conduit means to said reservoir.
 13. The machine of claim 11, and including third valve means connected in said second conduit means for opening and closing said second conduit means, said third valve means being arranged to open and close in unison with said first valve means.
 14. The machine of claim 13, and including second bypass conduit means connecting the portion of said second conduit means located between said second valve means and the motor with the reservoir, fourth valve means located in said second bypass conduit means, and means responsive to a given decrease in fluid pressure in said portion of the second conduit means when said third valve means is closed due to reverse travel of said machine down an incline for opening said fourth valve means and permitting flow of fluid to said portion of the second conduit means.
 15. In a machine adapted to perfOrm a working operation on a surface, a self-propelled vehicle having a pair of wheels and having a tank to receive material removed from the surface, means connected to the vehicle for engaging the surface and conveying the material from the surface to said tank on the vehicle, a first hydraulic circuit, a first hydraulic motor operably connected to one of said wheels and connected in said hydraulic circuit, a second hydraulic motor operably connected to a second of said wheels and connected in said hydraulic circuit in parallel with said first motor, first valve means connected in said hydraulic circuit in series with said first motor, second valve means connected in said hydraulic circuit in series with said second motor, and third valve means connected in said hydraulic circuit and arranged in parallel with said first and second valve means so that opening of said third valve means will bypass said first and second valve means and operate said first and second motors.
 16. The machine of claim 15, wherein said vehicle has a second pair of wheels, and said machine includes a third motor operably connected to a first of said second pair of wheels, a fourth motor connected to the second of said second pair of wheels, a second hydraulic circuit with said third and fourth motors being connected in parallel in said second hydraulic circuit, fourth valve means connected in said second hydraulic circuit in series with said third motor, fifth valve means connected in said second hydraulic circuit in series with said fourth motor, and sixth valve means connected in said second hydraulic circuit in parallel with said fourth and fifth valve means and arranged so that opening of said sixth valve means will bypass said fourth and fifth valve means and supply hydraulic fluid to both said third and fourth motors.
 17. The machine of claim 15, wherein said first pair of wheels are located on one side of the vehicle and the second pair of wheels are located on the opposite side of the vehicle. 